/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.messaging.converter;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.lang.reflect.Type;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicReference;

import com.fasterxml.jackson.annotation.JsonView;
import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;
import com.fasterxml.jackson.databind.DeserializationFeature;
import com.fasterxml.jackson.databind.JavaType;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.MapperFeature;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import org.springframework.core.GenericTypeResolver;
import org.springframework.core.MethodParameter;
import org.springframework.lang.Nullable;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageHeaders;
import org.springframework.util.Assert;
import org.springframework.util.MimeType;

/**
 * A Jackson 2 based {@link MessageConverter} implementation.
 *
 * <p>It customizes Jackson's default properties with the following ones:
 * <ul>
 * <li>{@link MapperFeature#DEFAULT_VIEW_INCLUSION} is disabled</li>
 * <li>{@link DeserializationFeature#FAIL_ON_UNKNOWN_PROPERTIES} is disabled</li>
 * </ul>
 *
 * <p>Compatible with Jackson 2.9 and higher, as of Spring 5.1.
 *
 * @author Rossen Stoyanchev
 * @author Juergen Hoeller
 * @author Sebastien Deleuze
 * @since 4.0
 */
public class MappingJackson2MessageConverter extends AbstractMessageConverter {

    private ObjectMapper objectMapper;

    @Nullable
    private Boolean prettyPrint;


    /**
     * Construct a {@code MappingJackson2MessageConverter} supporting
     * the {@code application/json} MIME type with {@code UTF-8} character set.
     */
    public MappingJackson2MessageConverter() {
        super(new MimeType("application", "json", StandardCharsets.UTF_8));
        this.objectMapper = initObjectMapper();
    }

    /**
     * Construct a {@code MappingJackson2MessageConverter} supporting
     * one or more custom MIME types.
     *
     * @param supportedMimeTypes the supported MIME types
     * @since 4.1.5
     */
    public MappingJackson2MessageConverter(MimeType... supportedMimeTypes) {
        super(Arrays.asList(supportedMimeTypes));
        this.objectMapper = initObjectMapper();
    }


    private ObjectMapper initObjectMapper() {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure(MapperFeature.DEFAULT_VIEW_INCLUSION, false);
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        return objectMapper;
    }

    /**
     * Set the {@code ObjectMapper} for this converter.
     * If not set, a default {@link ObjectMapper#ObjectMapper() ObjectMapper} is used.
     * <p>Setting a custom-configured {@code ObjectMapper} is one way to take further
     * control of the JSON serialization process. For example, an extended
     * {@link com.fasterxml.jackson.databind.ser.SerializerFactory} can be
     * configured that provides custom serializers for specific types. The other
     * option for refining the serialization process is to use Jackson's provided
     * annotations on the types to be serialized, in which case a custom-configured
     * ObjectMapper is unnecessary.
     */
    public void setObjectMapper(ObjectMapper objectMapper) {
        Assert.notNull(objectMapper, "ObjectMapper must not be null");
        this.objectMapper = objectMapper;
        configurePrettyPrint();
    }

    /**
     * Return the underlying {@code ObjectMapper} for this converter.
     */
    public ObjectMapper getObjectMapper() {
        return this.objectMapper;
    }

    /**
     * Whether to use the {@link DefaultPrettyPrinter} when writing JSON.
     * This is a shortcut for setting up an {@code ObjectMapper} as follows:
     * <pre class="code">
     * ObjectMapper mapper = new ObjectMapper();
     * mapper.configure(SerializationFeature.INDENT_OUTPUT, true);
     * converter.setObjectMapper(mapper);
     * </pre>
     */
    public void setPrettyPrint(boolean prettyPrint) {
        this.prettyPrint = prettyPrint;
        configurePrettyPrint();
    }

    private void configurePrettyPrint() {
        if (this.prettyPrint != null) {
            this.objectMapper.configure(SerializationFeature.INDENT_OUTPUT, this.prettyPrint);
        }
    }

    @Override
    protected boolean canConvertFrom(Message<?> message, @Nullable Class<?> targetClass) {
        if (targetClass == null || !supportsMimeType(message.getHeaders())) {
            return false;
        }
        JavaType javaType = this.objectMapper.constructType(targetClass);
        AtomicReference<Throwable> causeRef = new AtomicReference<>();
        if (this.objectMapper.canDeserialize(javaType, causeRef)) {
            return true;
        }
        logWarningIfNecessary(javaType, causeRef.get());
        return false;
    }

    @Override
    protected boolean canConvertTo(Object payload, @Nullable MessageHeaders headers) {
        if (!supportsMimeType(headers)) {
            return false;
        }
        AtomicReference<Throwable> causeRef = new AtomicReference<>();
        if (this.objectMapper.canSerialize(payload.getClass(), causeRef)) {
            return true;
        }
        logWarningIfNecessary(payload.getClass(), causeRef.get());
        return false;
    }

    /**
     * Determine whether to log the given exception coming from a
     * {@link ObjectMapper#canDeserialize} / {@link ObjectMapper#canSerialize} check.
     *
     * @param type  the class that Jackson tested for (de-)serializability
     * @param cause the Jackson-thrown exception to evaluate
     *              (typically a {@link JsonMappingException})
     * @since 4.3
     */
    protected void logWarningIfNecessary(Type type, @Nullable Throwable cause) {
        if (cause == null) {
            return;
        }

        // Do not log warning for serializer not found (note: different message wording on Jackson 2.9)
        boolean debugLevel = (cause instanceof JsonMappingException && cause.getMessage().startsWith("Cannot find"));

        if (debugLevel ? logger.isDebugEnabled() : logger.isWarnEnabled()) {
            String msg = "Failed to evaluate Jackson " + (type instanceof JavaType ? "de" : "") +
                    "serialization for type [" + type + "]";
            if (debugLevel) {
                logger.debug(msg, cause);
            } else if (logger.isDebugEnabled()) {
                logger.warn(msg, cause);
            } else {
                logger.warn(msg + ": " + cause);
            }
        }
    }

    @Override
    protected boolean supports(Class<?> clazz) {
        // should not be called, since we override canConvertFrom/canConvertTo instead
        throw new UnsupportedOperationException();
    }

    @Override
    @Nullable
    protected Object convertFromInternal(Message<?> message, Class<?> targetClass, @Nullable Object conversionHint) {
        JavaType javaType = getJavaType(targetClass, conversionHint);
        Object payload = message.getPayload();
        Class<?> view = getSerializationView(conversionHint);
        // Note: in the view case, calling withType instead of forType for compatibility with Jackson <2.5
        try {
            if (payload instanceof byte[]) {
                if (view != null) {
                    return this.objectMapper.readerWithView(view).forType(javaType).readValue((byte[]) payload);
                } else {
                    return this.objectMapper.readValue((byte[]) payload, javaType);
                }
            } else {
                if (view != null) {
                    return this.objectMapper.readerWithView(view).forType(javaType).readValue(payload.toString());
                } else {
                    return this.objectMapper.readValue(payload.toString(), javaType);
                }
            }
        } catch (IOException ex) {
            throw new MessageConversionException(message, "Could not read JSON: " + ex.getMessage(), ex);
        }
    }

    private JavaType getJavaType(Class<?> targetClass, @Nullable Object conversionHint) {
        if (conversionHint instanceof MethodParameter) {
            MethodParameter param = (MethodParameter) conversionHint;
            param = param.nestedIfOptional();
            if (Message.class.isAssignableFrom(param.getParameterType())) {
                param = param.nested();
            }
            Type genericParameterType = param.getNestedGenericParameterType();
            Class<?> contextClass = param.getContainingClass();
            Type type = GenericTypeResolver.resolveType(genericParameterType, contextClass);
            return this.objectMapper.getTypeFactory().constructType(type);
        }
        return this.objectMapper.constructType(targetClass);
    }

    @Override
    @Nullable
    protected Object convertToInternal(Object payload, @Nullable MessageHeaders headers,
                                       @Nullable Object conversionHint) {

        try {
            Class<?> view = getSerializationView(conversionHint);
            if (byte[].class == getSerializedPayloadClass()) {
                ByteArrayOutputStream out = new ByteArrayOutputStream(1024);
                JsonEncoding encoding = getJsonEncoding(getMimeType(headers));
                JsonGenerator generator = this.objectMapper.getFactory().createGenerator(out, encoding);
                if (view != null) {
                    this.objectMapper.writerWithView(view).writeValue(generator, payload);
                } else {
                    this.objectMapper.writeValue(generator, payload);
                }
                payload = out.toByteArray();
            } else {
                Writer writer = new StringWriter();
                if (view != null) {
                    this.objectMapper.writerWithView(view).writeValue(writer, payload);
                } else {
                    this.objectMapper.writeValue(writer, payload);
                }
                payload = writer.toString();
            }
        } catch (IOException ex) {
            throw new MessageConversionException("Could not write JSON: " + ex.getMessage(), ex);
        }
        return payload;
    }

    /**
     * Determine a Jackson serialization view based on the given conversion hint.
     *
     * @param conversionHint the conversion hint Object as passed into the
     *                       converter for the current conversion attempt
     * @return the serialization view class, or {@code null} if none
     * @since 4.2
     */
    @Nullable
    protected Class<?> getSerializationView(@Nullable Object conversionHint) {
        if (conversionHint instanceof MethodParameter) {
            MethodParameter param = (MethodParameter) conversionHint;
            JsonView annotation = (param.getParameterIndex() >= 0 ?
                    param.getParameterAnnotation(JsonView.class) : param.getMethodAnnotation(JsonView.class));
            if (annotation != null) {
                return extractViewClass(annotation, conversionHint);
            }
        } else if (conversionHint instanceof JsonView) {
            return extractViewClass((JsonView) conversionHint, conversionHint);
        } else if (conversionHint instanceof Class) {
            return (Class<?>) conversionHint;
        }

        // No JSON view specified...
        return null;
    }

    private Class<?> extractViewClass(JsonView annotation, Object conversionHint) {
        Class<?>[] classes = annotation.value();
        if (classes.length != 1) {
            throw new IllegalArgumentException(
                    "@JsonView only supported for handler methods with exactly 1 class argument: " + conversionHint);
        }
        return classes[0];
    }

    /**
     * Determine the JSON encoding to use for the given content type.
     *
     * @param contentType the MIME type from the MessageHeaders, if any
     * @return the JSON encoding to use (never {@code null})
     */
    protected JsonEncoding getJsonEncoding(@Nullable MimeType contentType) {
        if (contentType != null && (contentType.getCharset() != null)) {
            Charset charset = contentType.getCharset();
            for (JsonEncoding encoding : JsonEncoding.values()) {
                if (charset.name().equals(encoding.getJavaName())) {
                    return encoding;
                }
            }
        }
        return JsonEncoding.UTF8;
    }

}
